版本：22.0.5
硬件：swrast
入口：_mesa_DrawArrays

和i965的区别：

从 _mesa_draw_arrays 开始 Driver 重命名

ctx->Driver.DrawGallium(ctx, &info, 0, &draw, 1);

DrawGallium的加载

经过三层，从API到gallium、gllium到state tracker、再从state tracker到真正的driver。
进入state_tracker/st_draw.c

st_init_draw_functions(struct pipe_screen *screen,
                       struct dd_function_table *functions)
{
   functions->DrawGallium = st_draw_gallium;
   functions->DrawGalliumMultiMode = st_draw_gallium_multimode;

   if (screen->get_param(screen, PIPE_CAP_DRAW_VERTEX_STATE)) {
      functions->DrawGalliumVertexState = st_draw_gallium_vertex_state;
      functions->CreateGalliumVertexState = st_create_gallium_vertex_state;
   }
}

• st_init_draw_functions被调用的过程，draw函数的加载过程：
  从 eglCreateContext 中调用的

   context = disp->Driver->CreateContext(disp, conf, share, attrib_list);

const struct __DriverAPIRec galliumdrm_driver_api = {
   .InitScreen = dri2_init_screen,
   .DestroyScreen = dri_destroy_screen,
   .CreateContext = dri_create_context,
   .DestroyContext = dri_destroy_context,
   .CreateBuffer = dri2_create_buffer,
   .DestroyBuffer = dri_destroy_buffer,
   .MakeCurrent = dri_make_current,
   .UnbindContext = dri_unbind_context,

   .AllocateBuffer = dri2_allocate_buffer,
   .ReleaseBuffer  = dri2_release_buffer,
};

-> 到gallium/frontends/dri/dri_context.c: dri_create_context

   ctx->st = stapi->create_context(stapi, &screen->base, &attribs, &ctx_err,
                   st_share);

static const struct st_api st_gl_api = {
   .name = "Mesa " PACKAGE_VERSION,
   .api = ST_API_OPENGL,
   .profile_mask = ST_PROFILE_DEFAULT_MASK |
                   ST_PROFILE_OPENGL_CORE_MASK |
                   ST_PROFILE_OPENGL_ES1_MASK |
                   ST_PROFILE_OPENGL_ES2_MASK |
                   0,
   .feature_mask = ST_API_FEATURE_MS_VISUALS_MASK,
   .destroy = st_api_destroy,
   .query_versions = st_api_query_versions,
   .create_context = st_api_create_context,
   .make_current = st_api_make_current,
   .get_current = st_api_get_current,
   .destroy_drawable = st_api_destroy_drawable,
};

-> state_tracker/st_manager.c：st_api_create_context

   st = st_create_context(api, pipe, mode_ptr, shared_ctx,
                          &attribs->options, no_error,
                          !!smapi->validate_egl_image);

-> state_tracker/st_context.c：st_create_context

   st_init_driver_functions(pipe->screen, &funcs, has_egl_image_validate);

-> state_tracker/st_context.c：st_init_driver_functions

image.png

st_gl_api 的加载

state_tracker/st_manager.c：st_gl_api_create

struct st_api *
st_gl_api_create(void)
{
   return (struct st_api *) &st_gl_api;
}

-> gallium/frontends/dri/dri_screen.c: dri_init_screen_helper

   screen->st_api = st_gl_api_create();

-> gallium/frontends/dri/dri2.c: dri2_init_screen

   configs = dri_init_screen_helper(screen, pscreen);

dri2_init_screen接上面的gallium driver api： .InitScreen = dri2_init_screen,

-> gallium/frontends/dri/dri_util/c: driCreateNewScreen2

    *driver_configs = psp->driver->InitScreen(psp);

-> gallium/frontends/dri/dri_util/c: dri2CreateNewScreen

static __DRIscreen *
dri2CreateNewScreen(int scrn, int fd,
            const __DRIextension **extensions,
            const __DRIconfig ***driver_configs, void *data)
{
   return driCreateNewScreen2(scrn, fd, extensions, NULL,
                               driver_configs, data);
}

const __DRIdri2Extension driDRI2Extension = {
    .base = { __DRI_DRI2, 4 },

    .createNewScreen            = dri2CreateNewScreen,
    .createNewDrawable          = driCreateNewDrawable,
    .createNewContext           = driCreateNewContext,
    .getAPIMask                 = driGetAPIMask,
    .createNewContextForAPI     = driCreateNewContextForAPI,
    .allocateBuffer             = dri2AllocateBuffer,
    .releaseBuffer              = dri2ReleaseBuffer,
    .createContextAttribs       = driCreateContextAttribs,
    .createNewScreen2           = driCreateNewScreen2,
};

这里就和egl的API接上了，最终是到eglInitialize上了